Fragment eines Verschlussdeckel einer Warmluftaustrittsöffnung einer mittelalterlichen Luftheizung

This ceramic plate probably belonged to a heat storage hypocaust system in the Dominican monastery - a seemingly simple but ingenious construction. The friars would light a fire in a furnace vault in order to heat the stones above it. The air between the hot stones would heat up and flow through a system of pipes into the rooms in the upper storeys. To prevent smoke from reaching the rooms, the friars put such plates over the openings while the fire was burning.